Where can I find a document's or folder's GUID for the FLD_MOVE service?

Question

We are currently migrating to Webcenter Content 11.1.1.6 using FrameworkFolders. We need to integrate with several other systems to check-in and retrieve files and would like to place our content in a folder-based heirarchy. I have been using the Generic Web Service to perform integration functions.
I am trying to use the Folders Services to get information about folders and place files into specific folders.
First of all, if I check in a file using the "CHECKIN_NEW" service, what folder does the file go into? I can search for the file, but it doesn't seem to belong to a folder? As far as I can tell, the only way to retrieve the file is to search for it. Shouldn't it go to some folder by default?
Second, lets say I want to move that file to a folder. The "FLD_MOVE" service seems to be what one would use to place a file into a folder. The parameter (item1) that is used to identify what you want to move can take either a GUID or a path to the file. I can't use a path since the file doesn't seem to have a path. I have tried using the dID and the dDocName as the GUID parameter, but the service always comes back and says my item does not exist.
I can't find any other kind of unique identifier for my document. I have searched and searched for what the GUID could be and how to find out what it is. GUID seems to be specific to the Contribution Folders and Folders Service, as none of the other services reference GUID.
What is a GUID and how can I figure out what a document's GUID is?

Answer 1

Very good advice on turning on the auditing. I found a link to how to do this in another post. It seems the documentation around the services lacks the information necessary to use them, but the audit logs can reveal what parameters need to be used to perform an action.
Turn on server-wide tracing for request audit http://docs.oracle.com/cd/E23943_01/doc.1111/e10792/c03_processes.htm#CSMSP536 and then create the link from GUI (maybe DIS). You will find your answer in the Server Output.
By turning on the audit logs and using the browser UI to place a document into a folder, I found this in the audit log (cleaned up for readability):
IdcService=FLD_CREATE_FILE
fFileType=owner
fParentGUID=3BCD5A4050F2D10D9C0A0CF3CC8840C1
dialogCounter=4
dDocName=USTST-PFARPIM000808
constructDidCreateLinkDialog=1
dID=807
idcToken=1370802991160%3A01FCE7B4B65CB3E48EDC2A1982C62526
constructDidCreateLinkDialog=1
IsJson=1
Calling the web service using the parameters in bold performed the folder assignment of a document using the document's docName value (which is readily available in the GUI).
Thanks!